This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 23 |
| 4 | 84 |
| 5 | 605 |
| 6 | 2806 |
| 7 | 17107 |
| 8 | 87528 |
| 9 | 500089 |
| 10 | 2663210 |
| 11 | 14828111 |
| 12 | 80257212 |
| 13 | 442248533 |
| 14 | 2409384094 |
| 15 | 13221490315 |
| 16 | 72221278416 |
| 17 | 395650872817 |
| 18 | 2163506035538 |
| 19 | 11844378654599 |
| 20 | 64795371984420 |
| 21 | 354633938406221 |